This invention relates to a positive crankcase ventilation system, more particularly, the invention relates to a positive crankcase ventilation system for integration into a intake manifold assembly.
An air/fuel mixture is delivered to a combustion chamber of an internal combustion engine by an intake manifold assembly. The air/fuel mixture is ignited in the combustion chamber thereby forcing the piston down and generating rotary motion through a crankshaft. Piston rings create a seal between the piston and the wall of the combustion chamber to prevent combustion gases from entering the crankcase of the engine block. Additionally, the piston rings prevent oil in the engine crankcase from entering the combustion side of the combustion chamber. However, due to the high gas forces generated during the combustion process, some combustion gases "blow by" the piston rings and enter the crankcase.
It is undesirable for combustion gases to enter the crankcase because the pressure in the crankcase is raised and the combustion gases mix with the oil and degrade the oil. Accordingly, crankcase ventilation systems are used to vent the combustion gases from the crankcase. Modern crankcase ventilation systems re-circulate the gas to the intake manifold where it may be delivered to the combustion chamber for combustion. Crankcase ventilation systems incorporate a positive crankcase ventilation (PCV) valve that is typically received in the opening of a rocker cover. A hose is routed from the PCV valve to a vacuum source in the intake manifold, which draws the scavenged gases from the crankcase to the combustion chamber. The rocker cover typically includes a separator having baffles that separates the gases and oil mist. The PCV valve is vacuum actuated to permit scavenged gases to enter the intake manifold when the introduction of the gases will least negatively impact engine performance.
The location of the PCV valve external to the engine and the use of hoses to route the scavenged gases to the intake manifold may permit the scavenged gases to leak from the positive crankcase ventilation system thereby generating unacceptable emissions. This is of great concern with strict emissions requirements common today. Accordingly, what is needed is a positive crankcase ventilation system that is located within an engine component and eliminates the use of hoses to reduce the possibility of unwanted emissions.